Coalescing scandals have engulfed Virginia’s leaders, plunging the state into political free fall.

First, Gov. Ralph Northam came under fire for a racist yearbook photo, which he acknowledged and then denied appearing in. He also admitted to wearing blackface to dress up as Michael Jackson in the 1980s.

Then Lt. Gov. Justin E. Fairfax was accused of sexual assault by two women, allegations he has strongly denied. And the state’s third-ranking elected official in Virginia, Attorney General Mark R. Herring, has acknowledged that he, too, wore blackface as a younger man.

Only a week ago, it seemed that Mr. Fairfax, who is African-American, was poised to ascend to the governorship and lead Virginia through a reckoning with its painful history on race. But now he is facing the threat of impeachment proceedings, while the state’s other two top leaders, both white, are resisting calls to quit over past racist conduct.

Here is what the law says about removing Virginia politicians from office, why Mr. Fairfax’s case could throw gasoline on this political fire and what could happen next if Mr. Fairfax were to be forced out of office.

[Catching up? Read this timeline of how the scandals unfolded over nine days in Virginia.]

What is the line of succession in Virginia?

Mr. Northam has so far withstood calls for his resignation. But if he were to step down, Mr. Fairfax is next in line, followed by Mr. Herring, the attorney general. All three are Democrats.

If all three men — Mr. Northam, Mr. Fairfax and Mr. Herring — were to resign without immediate replacements, Kirk Cox, the Republican speaker of the House of Delegates, would become governor. “I have never been in blackface, unequivocal,” Mr. Cox said this past week.

If they don’t resign, what is the bar for removal?

In the case of the governor, there are two possible paths for removal: He could be impeached for “malfeasance in office, corruption, neglect of duty, or other high crime or misdemeanor,” according to the Virginia Constitution. Or he could be removed in the event that he is physically or mentally unfit for office, according to John Dinan, a professor of politics at Wake Forest University who wrote a book on the Virginia Constitution.

It would be difficult to remove Mr. Northam from office over the current allegations on either basis, Dr. Dinan said.

The lieutenant governor and attorney general can be removed only through impeachment, which could also be an “uphill challenge” in these cases, Dr. Dinan said.

“Impeachment is seen as applying to a limited set of cases, generally committed while one is in office or in the pursuit of office,” he said.

The blackface incidents involving the governor and attorney general date to the 1980s, and Mr. Fairfax, who was sworn in as lieutenant governor last year, is accused of sexual assault in two cases from the 2000s.

Why is Justin Fairfax at risk of removal?

Experts said the case for impeachment against Mr. Fairfax could be stronger because he is accused of serious criminal conduct.

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Protesters and activists marching near the Virginia State Capitol after Gov. Ralph Northam came under fire for a racist yearbook photo and an admission that he wore blackface as a costume in the 1980s.CreditParker Michels-Boyce for The New York Times

Vanessa C. Tyson, a professor of political science from California, recently came forward to say she was sexually assaulted by Mr. Fairfax during the 2004 Democratic National Convention in Boston. It began with kissing that was “not unwelcome,” she said, but quickly escalated into nonconsensual oral sex.

Mr. Fairfax has denied the accusations and called for an investigation.

While Mr. Fairfax and Mr. Northam have both been besieged by calls to step down, Mr. Fairfax is now the one facing an imminent threat of removal. A Democratic state legislator has vowed to introduce articles of impeachment if Mr. Fairfax does not quit by Monday.

Impeachment and removal would require a majority vote in the Virginia House of Delegates and support from two-thirds of the State Senate, experts said. Virginia’s legislature is narrowly controlled by Republicans, although Mr. Fairfax has also lost support within his party.

“Things look rather dim for him,” said Larry J. Sabato, the director of the Center for Politics at the University of Virginia. But he cautioned against speculation in the midst of a political storm.

“Remember,” he said, “a week ago, we thought the lights were out for Northam.”

If the lieutenant governor office opens up, what would happen next?

There is no clear succession plan should Mr. Fairfax leave office, and because of conflicting laws and interpretations, a political fight could explode over how to replace him.

The Virginia Constitution says that when there is no explicit provision for how to fill a vacancy, the governor appoints a replacement to serve until the next regularly scheduled election. “It’s the catchall clause,” said Dr. Dinan.

Separately, a Virginia law says that if the lieutenant governor’s office is vacant, the president pro tempore of the State Senate would “discharge the duties of the office,” Dr. Dinan said. But the Constitution makes a point to say that is not the same thing as filling a vacancy, he said. The president pro tempore “is just discharging the duties temporarily,” he said.

In 1982, the attorney general’s office weighed in on the conflict in a ruling that said “the governor has the discretionary power to fill a vacancy in the office of lieutenant governor.”

Senior Virginia Democrats are making the case that Mr. Northam should appoint State Senator Jennifer McClellan to replace Mr. Fairfax. Ms. McClellan, who is black, is a longtime Richmond legislator who has a close relationship with United States Senator Tim Kaine.

But political opponents of Mr. Northam are likely to balk at allowing him to choose the next lieutenant governor, at a time when he is under a cloud of mistrust.

Either way, experts said the solution would most likely be short term, until voters could elect a long-term replacement in a special election in November.

“There is no way to know for sure how this is going to play out,” Dr. Sabato said.